1. Field of the Invention
The present invention relates to an ADSL communication modem apparatus that adheres to the ITU-T recommended G.992.1 (hereafter referred to as G.dmt) and G.992.2 (hereafter referred to as G.lite), and an ADSL communication and an ADSL communication method that improve the above communication method.
2. Description of Related Art
During an ADSL communication based on ANNEX.C of G.hs/G.lite, carriers of carrier indexes #48 and #64 are used for a C-PILOT signal (C-PILOT1 signal or C-PILOT1A (accompanied pilot) signal), which are included in a downstream of an initialization sequence. This PILOT signal is used in order to establish a hyperframe synchronization at the remote side. When the center and remote sides establish both hyperframe synchronization and symbol synchronization, it is possible to accurately count and recognize each symbol for an important signal, and to execute communication sequences.
However, carrier frequencies (#48 and #64) assigned to the PILOT signal included in the downstream have a large attenuation amount during a long distance communication, due to their high frequencies, thereby preventing an adequate communication and hindering the realization of long distance ADSL communications.